(a) Field of the Invention
This invention relates to cardiotonic compositions and method for increasing cardiac contractility using 4-[4(or 3)-aminophenyl]pyridines or acyl derivatives thereof, and to certain 4-[4(or 3)-acylaminophenyl]pyridines and their preparation.
(b) Description of the Prior Art
Heilbron et al [J. Chem. Soc. 1940, 1279] show as intermediates in the preparation of 3- and 4-pyridyldiphenyls the following compounds: .beta.-3-aminophenylpyridine, .beta.-4-aminophenylpyridine and .gamma.-4-aminophenylpyridine and the N-acetyl derivatives of each, including the hydrochloride salt of .beta.-4-acetamidophenylpyridine; these three aminophenylpyridines currently are named 3-(3-pyridinyl)benzeneamine, 4-(3-pyridinyl)benzeneamine and 4-(4-pyridinyl)benzeneamine, respectively.
Lesher and Carabateas [U.S. Pat. Nos. 3,753,993 (8-21-73) and 3,907,808 (9-23-75)] show as intermediates for making quinoline antibacterial agents various 3-(substituted-pyridinyl)benzeneamines where pyridinyl is substituted, inter alia, by lower-alkyl, hydroxyl, etc., illustrated by, 3-(2-methyl-4-pyridinyl)benzeneamine, 3-(2-hydroxy-6-methyl-4-pyridinyl)benzeneamine, 3-(2,6-dimethyl-4-pyridinyl)benzeneamine, 3-(2,6-diethyl-4-pyridinyl)benzeneamine, 3-(2,5-dimethyl-4-pyridinyl)benzeneamine, 3-(3-methyl-4-pyridinyl)benzeneamine, 3-(2-ethyl-4-pyridinyl)benzeneamine, and 3-(2,3-dimethyl-4-pyridinyl)benzeneamine.
Lesher [U.S. Pat. No. 4,118,557, issued Oct. 3, 1978] shows N-(lower-alkanoyl)derivatives of various 3-(pyridinyl)benzeneamines, as illustrated as follows: N-acetyl, N-formyl, N-propanoyl, N-butanoyl and N-hexanoyl derivatives of 3-(4-pyridinyl)benzeneamine; and, the N-acetyl derivatives of 3-(2-methyl-4-pyridinyl)benzeneamine, 3-(3-pyridinyl)benzeneamine, 3-(2,6-dimethyl-4-pyridinyl)benzeneamine and 3-(2-ethyl-4-pyridinyl)benzeneamine.